1. Field of the Invention
The present invention relates to a method for concentrating subscribers in a local exchange.
2. Description of the Related Art
V5 interface standards ETS 300 324 and ETS 300 347 describe an interface between a local exchange and an access network and the functionality in each network element. The access network is the part of a local area network that contains the subscriber""s lines. Thus, subscribers and subscriber""s lines can be connected to the exchange either directly (direct subscribers) or via various multiplexers and/or concentrators. V5 interfaces enable subscribers belonging to a physically separate access network to be connected to a local exchange using a standard interface.
A static V5.1 multiplexer interface consistent with the ETS 300 324 standard series consists of one 2048 kbit/s PCM line. The V5.1 interface supports analogue telephones as used in the public telephone network, digital, such as ISDN (Integrated Services Digital Network) basic subscriber lines as well as other analogue or digital terminal equipment based on semifixed connections.
At present, the V5.1 interface is implemented in the local exchange in a manner that permits one V5.1 concentrator to be connected to one exchange terminal. The exchange terminal is further connected to the group switch of the local exchange via a single PCM line with a transmission capacity corresponding to that of the V5.1 interface, which preferably is 2 Mbit/s. Thus, the link between the exchange terminal and the group switch comprises no concentration of speech time slots, i.e. B-channels, because the V5.1 interface contains as many time slots as the interconnecting line between the exchange terminal and the group switch, preferably 30 time slots.
Therefore, these circumstances involve the problem that, if a plurality of V5.1 interfaces are to be connected to the local exchange, the latter must be provided with as many exchange terminals, thus increasing the size and cost of the local exchange.
The object of the present invention is to eliminate the problem described above. A specific object of the present invention is to produce a solution in which concentration of time slots is implemented between the exchange terminal and the group switch and the number of exchange terminals in the local exchange is reduced.
As for the features characteristic of the invention, reference is made to the claims.
In the method of the invention for concentrating subscribers, preferably V5 subscribers in a local exchange, the subscribers are connected to the group switch via a link between an exchange terminal and the group switch, said link being preferably implemented using one or more PCM lines with a capacity of 2 Mbit/s. The local exchange preferably comprises an exchange terminal that serves to form a V5 interface in the exchange, and a group switch known in itself.
According to the invention, several V5 interfaces are connected to a single exchange terminal and the exchange terminal is connected to the group switch via an interconnecting line, thus forming between the exchange terminal and the group switch an internal interface within the local exchange for concentrating V5 subscribers. The degree of concentration can be further increased by combining a number of exchange terminals into a single exchange terminal cassette, which is further connected to the group switch via a single interconnecting line. A limiting factor in the concentration of subscribers is the capacity they need, which has to be checked when concentration is being planned.
As compared with prior art, the present invention has the advantage that it allows concentration that makes it possible to reduce the exchange terminal capacity needed for V5.1 subscribers in the local exchange. Moreover, the invention enables the wiring and structures in the local exchange to be simplified, which further reduces the costs and facilitates the assembly of a local exchange.
The exchange terminal used is preferably a V5.1 subscriber module controller. In addition, time slot data and/or V5 interface data regarding the V5 interface used by the subscriber is/are stored in a subscriber database, said data being used when scanning and designating a free time slot for the subscriber in the interconnecting line between the group switch and the exchange terminal during call setup. Information regarding the time slot designated for the subscriber in the interconnecting line is supplied to the exchange terminal to which the V5 interface used by the subscriber is connected, so that the exchange terminal will be able to connect the subscriber""s V5 interface time slot to the correct time slot in the interconnecting line between the exchange terminal and the group switch. The designation of a time slot in the interconnecting line is preferably done specifically for each call, which means dynamic allocation of resources in the interconnecting line.
The access network is preferably connected to the local exchange via a V5 interface. This V5 interface may be a standard V5.1 or V5.2 interface.